Stars from two shows on cable T-V’s “Animal Planet” channel are visiting Iowa’s largest zoo for this weekend’s Animal Planet Expo. The event at Blank Park Zoo in Des Moines features pet contests, pet safety, rescue relays and pet auditions for upcoming shows. Veterinarian Dr. Kevin Fitzgerald, host of “Emergency Vets,” says a man appeared at another expo a few weeks ago with a dog that could do math, including square roots. Animals are trained to do all sorts of things — including dogs that skateboard, a rat that can play basketball, a groundhog that can raise a flag and the now-famous water skiing squirrel. Other stars in Des Moines for the expo include Mario Lopez, the host of “Pet Star,” and the show’s producer, Richard Crystal, the brother of actor/comedian Billy Crystal. Dr. Fitzgerald is visiting a number of central Iowa schools and hospitals today (Friday), meeting with kids and other animal lovers. He shows kids footprints of various Iowa animals and has them try to guess what creatures made the prints — everything including: skunks, porcupines, raccoons, hawks, deer, fox and others. The Animal Planet Expo is a free event that will be open to the public at Blank Park from 10 AM to 4 PM on Saturday and Sunday. A similar Animal Planet Expo is planned for Cedar Rapids next weekend.